This invention relates to a hole saw and, more particularly, to a self-centering adapter for use therewith.
In the military establishment there has arisen the requirement to make circular cut outs in aircraft engine bays for the removal of foreign objects. This requirement includes cutting out circular holes two (2) inches in diameter in the aircraft engine bays; or, if a patched hole already exists, removing the patch covering the hole and enlarging it to the required two (2) inches. In this regard, it is to be noted that: preexisting man-made holes in aircraft engine bays are typically circular; they penetrate both an outer skin layer and an inner blanket layer, to the rear of which is a fuel tank; they have a diameter of three-quarters of one inch; they are each covered on the outer skin layer by and with a hard metal circular path of two (2) inches; and, the patch is riveted to the engine bay skin. It is also to be noted that there are twenty-three (23) holes to be cut in each engine bay; that a path is typically riveted to a preexisting hole by a plurality of rivets, usually six; and; that the cutting out, or the patch removal and subsequent cutting out, are to be accomplished with and by the use of a hole saw driven by a drill. It is further to be noted that the removal of a riveted patch presently involves the method which includes the steps of: drilling a small hole in the center of the patch to allow the one-quarter of an inch shaft of a hole saw to fit snugly in the drilled hole; next, positioning the shaft of the hole saw into the drilled hole, in an attempt to stabilize the hole saw; the hole saw is activated (i.e., rotated by the drill); the patch is cut out; and, the skin layer and the blanket layer are cut out, hopefully without cutting into and through the fuel tank.
The substantial problems generated by the use of this riveted patch removal method include, but are not limited to the following: since the man-made hole under the patch is typically three-quarters of one inch, the one-quarter of an inch hole saw shaft wobbles in the one-quarter inch hole drilled in the patch, causing undesired and unintended irregularly shaped cut outs, or cut outs that are larger than necessary; and, since the diameter of the hole saw typically used is just inside of the diameter of the patch to be cut out, the hole saw wears out after two or three patches are cut out, because of the double thickness and the hardness of the patch; and also, since the cut out includes the blanket layer adjacent to the fuel tank, there is the risk of cutting into and through the fuel tank.
My adapter, when used with the hole saw and shaft typically used, nevertheless eliminates these problems, while attaining the desired and intended results. With my inventive adapter, I have thereby significantly advanced the state-of-the-art.